J. Migdalek

Relativistic oscillator strengths and excitation energies for the ns2 1S0-nsnp 3P1, 1P1 transitions. II. Cadmium isoelectronic sequence

For pt.I see ibid., vol.18, no.8, p.1533 (1985). Relativistic excitation energies and oscillator strengths for both the resonance transition 5s2 1S0-5s5p 1P1 and the intercombination lines 5s2 1S0-5s5p 3P1 in the cadmium isoelectronic sequence are computed in an approach which combines limited relativistic configuration mixing to represent intravalence correlation with a polarisation model to account for valence-core correlation. This approach is able to greatly reduce the discrepancies between the theoretical and experimental oscillator strengths for these transitions. A substantial part of the remaining discrepancy, particularly for ionised systems, can probably be attributed to uncertainties in the available experimental data. Systematic trends along the sequence in both the oscillator strengths and in the relative contributions of intravalence and valence-core electron correlation are discussed and compared with those obtained previously for the mercury sequence. It is found that for spin-allowed transitions the share of intravalence correlation increases for lighter (lower Z) homologous systems in corresponding ionisation stages, whereas that of core-valence correlation decreases. For the spin-forbidden transitions, however, both correlation contributions seem to increase for lower Z homologues in the same ionisation stages.

Influence of atomic core polarisation on oscillator strengths for 2S1/2-2P1/2,3/2 and 2P1/2,3/2-2D3/2,5/2 transitions in Cu I, Ag I and Au I spectra

The recently proposed model potential for including correlation effects in relativistic Hartree-Fock calculations is applied to computations of oscillator strengths for the lowest transitions in Cu I, Ag I and Au I spectra. The present results remove the large discrepancies between the measured fik values for resonance transitions and the values from single-configuration calculations.

Influence of core polarisation on oscillator strengths along the copper isoelectronic sequence

The influence of core polarisation on relativistic oscillator strengths has been studied for the 4s2S12/-4p2P1/2,3/2 and 4p2P1/2,3/2-4d2D3/2,5/2 transitions along the copper isoelectronic sequence. Core polarisation effects are included in a relativistic Hartree-Fock method as well as in a relativistic semi-empirical model-potential approach by introducing a core polarisation potential in the calculation of wavefunctions and by employing the corresponding correction for the dipole moment operator in the transition matrix element. The results obtained are compared with available theoretical and experimental data and the influence of core polarisation effects is discussed.

Relativistic Hartree-Fock oscillator strengths for lowest np2P1/2,3/2 to (n+1)s2S1/2 and np2P1/2,3/2 to nd2D3/2,5/2 transitions in Ga I, In I and Tl I with allowance for core polarisation

Oscillator strengths determined from single-configuration relativistic Hartree-Fock (RHF) calculations are reported for the lowest np2P1/2,3/2 to (n+1)s2S1/2 and np2P1/2,3/2 to nd2D3/2,5/2 transitions in Ga I, In I and Tl I. Core-polarisation effects are included in the RHF calculation by introducing a polarisation potential in the one-electron Hamiltonian as well as by employing the corresponding correction to the dipole moment operator in the transition matrix element.

Relativistic oscillator strengths for the 6s2 1S0-6s6p 3P1, 1P1 transitions in neutral mercury. A new approach to the correlation problem

A new approach to calculations of correlation effects is described and applied to neutral mercury. In this approach limited relativistic configuration mixing to represent intravalence correlation is combined with a polarisation model to account for valence-core correlation. Calculations without parameter adjustment give excitation energies and oscillator strengths for both the resonance transition 6s2 1S0-6s6p 1P1 and the intercombination line 6s2 1S0-6s6p 3P1 which are in good agreement with experiment.

Relativistic transition probabilities and lifetimes of low-lying levels in ytterbium

Multiconfiguration Dirac-Fock calculations of E1, E2, M1 and M2 transition probabilities and lifetimes for the low-lying levels of neutral ytterbium are reported. For E1 transitions the valence-core electron correlations are also included in the core-polarization model. In particular, the lifetimes of the 6s6p1P1 and 3P1 states, when corrected for core polarization, are 4.78 ns and 1294 ns, respectively. The lifetime of the metastable 6s6p 3P2 state is calculated to be 14.5 s.